What it is
CVE-2020-11991 is an unauthenticated vulnerability affecting Apache Cocoon. When using the StreamGenerator, the code parse a user-provided XML. A specially crafted XML, including external system entities, could be...
Vulnerability report
Active exploitation observed
Confirmed confidence
Not in CISA KEV
CVE-2020-11991
Cocoon
Apache / Cocoon · Apache Cocoon 2.1.0 to 2.1.12
- Severity
- CVSS 7.5 · High
- Confidence
- Confirmed
- Exploit status
- Observed in sensors
- EPSS
- 72.5%
- First observed
- 27 Jun 2026
- Last observed
- 23 Jul 2026
Decision summary
What security teams need to know first
Direct answers before the deeper technical record.
Is it exploited?
Yes. KEVIntel sensors observed exploitation attempts with confirmed confidence.
Who is affected?
Apache / Cocoon apache cocoon 2.1.0 to 2.1.12.
What should we do?
Patch immediately, validate internet-facing exposure, and monitor for matching requests.
Overview
When using the StreamGenerator, the code parse a user-provided XML
When using the StreamGenerator, the code parse a user-provided XML. A specially crafted XML, including external system entities, could be used to access any file on the server system.
Vendor
Product
Affected
Status
n/a
Apache Cocoon
Apache Cocoon 2.1.0 to 2.1.12
Affected
- Published
- 11 Sep 2020
- Exploitation Reported
- 29 Jul 2025
- Attack vector
- Remote
- Complexity
- Low
- Privileges
- None
- User interaction
- None
Tags
nuclei_scanner
apache
CVE References
- Apache Mailing List lists.apache.org · CVE Record https://lists.apache.org/thread.html/r77add973ea521185e1a90aca00ba9da...
Exploitation evidence
Why KEVIntel marks this CVE as exploited
Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.
Exploited in the wild
The Shadowserver
Independent exploitation attestation added to the KEVIntel record.
Active exploitation observed
KEVIntel sensor
First-party sensor telemetry confirms matching exploitation attempts.
Proof of concept available
Nuclei Templates
Public scanner or PoC coverage increases practical exploitability.
Known exploited vulnerability sources
Per-source evidence links for KEV attestations are available through the KEVIntel Pro API.
Learn about Pro API access| Source | Added |
|---|---|
| The Shadowserver First | 2025-07-29 00:00 UTC |
| KEVIntel | 2026-07-23 11:17 UTC |
Operational indicators for this CVE are listed under Detection.
Sensor telemetry
First-party evidence of exploitation activity
Aggregate observations show the scale, recency, and distribution of activity without overstating sparse data.
2
Attempts observed
2
Unique attacker IPs
2
Attacker countries
NL · US
2
Sensors observed
Exploitation attempts over the last 41 days
Daily events observed by KEVIntel sensors
Updated 05 Aug 2026
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First observed 27 Jun 2026 · Last observed 23 Jul 2026
Pro adds sensor region and window summaries. Enterprise adds raw IPs, paths, User-Agents, and payloads.
Detection
Operational artifacts and observed signals
Make the evidence actionable in scanner, SOC, and edge-control workflows.
Observed signals
- Request targets
- 1
- User-Agents
- 2
Raw values available in Pro and Enterprise.
Scanner coverage
Nuclei template detected 25 Apr 2025.
View Nuclei template (opens in new tab)Virtual patch status
No KEVIntel virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.
Learn about virtual patches →Attacker IP Indicators
Attacker IP indicators observed · available in Pro and Enterprise.
Sensor-derived attacker IP indicators are available to Pro and Enterprise accounts under Detection and through the Pro API.
Learn about Pro API accessScanner Artifacts
Scanner and exploit-framework references linked to this CVE.
| Scanner | Reference | Detected |
|---|---|---|
| Nuclei | https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2020/CVE-2020-11991.yaml | 25 Apr 2025 |
Risk and context
Severity, weaknesses, and research context
CVSS v3.1
7.5
High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
EPSS
72.5%
All CVSS Scores
CVSS v3.1
7.5
High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CVSS v2.0
5.0
Medium
AV:N/AC:L/Au:N/C:P/I:N/A:N
Potential Proof of Concepts
These PoCs are unverified and could contain malware. Use at your own risk.
Apache Cocoon 2.1.12 - XML Injection
nuclei · Created Unknown
Timeline
From disclosure to observed exploitation
-
Observed by KEVIntel sensors
Evidence-backed exploitation signal
-
Indicators of compromise added (22)
Indicators of compromise recorded
-
Public PoC available
Public proof-of-concept code published
-
Added to KEVIntel KEV Feed
High-confidence, third-party attested exploitation
-
Nuclei template available
Scanner coverage available
-
CVE published
Vulnerability disclosed publicly
-
CVE ID reserved
Identifier reserved by the CNA
Pro API
Automate this intelligence
Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.
- Evidence confidence and provenance
- First-party sensor telemetry
- PoC and scanner references
- Affected versions and enrichment
- Automation-ready JSON delivery
GET /api/v2/pro/kevs/CVE-2020-11991
Free JSON includes basic KEV fields{
"cve_id": "CVE-2020-11991",
"confidence": "Confirmed",
"cvss_score": 7.5,
"epss_score": 0.72456,
"exploit_status": {
"exploited_in_the_wild": true,
"active_exploitation_observed": true
},
"sensor_telemetry": { "attempts": 2, "sensors": 2 }
}